Irradiation Mediates <i>IFNα</i> and <i>CXCL9</i> Expression in Non-Small Cell Lung Cancer to Stimulate CD8⁺ T Cells Activity and Migration toward Tumors

Abstract

Irradiation-broken DNA fragments increase type I interferon and chemokines secretion in tumor cells. Since radiotherapy may augment tumor immunotherapy, we hypothesize that the chemokines increased by irradiation could recruit CD8+ T cells to suppress tumor proliferation. This study intended to unveil the secreted factors activating and recruiting CD8+ T cells in non-small-cell lung cancer (NSCLC). EGFR-positive A549 was selected and treated by X-irradiation (IR) to identify the overexpression of chemokines associated to CD8+ T cell cytotoxicity and recruitment. A transwell assay with Alexa 488-labeled CD8+ T cells was used to evaluate CD8+ T cell motility in vitro. A nuclear imaging platform by In111-labeled nivolumab was used to track CD8+ T cells homing to tumors in vivo. The activation markers GZMB, PRF-1, and IFNγ, migration marker CD183 (CXCR3), and inhibitory marker CD274 (PD-1), were measured and compared in CD8+ T cells with A549 co-cultured, chemokines treated, and patients with late-stage lung cancer. We found that IR not only suppressed A549 proliferation but also induced IFNα and CXCL9 expression (p IFNα majorly increased IFNγ levels in CD8+ T cells (p CXCL9 enhanced CD8+ T cell migration in vitro (p + T cells in patients with lung cancer (n = 4 vs. healthy n = 3, both p p + T cells migrated to A549-induced tumors. In addition, we demonstrated that healthy PBMCs significantly suppressed the parallel tumor growth (p p IFNα and CXCL9 expression in A549 cells, leading to CD8+ T cell migration. This study unveiled a potential mechanism for radiotherapy to activate and recruit CD8+ T cells to suppress lung tumors.

Keywords

• non-small-cell lung cancer
• <i>IFNα</i>
• <i>CXCL9</i>
• CXCR3
• PD-1
• CD8⁺ T cells